how can a scan be right in respect of how many weeks pregnant you are

[andii66]

i dont understand how a scan be right i went for my second early scan last week and they said i was approx 6 weeks pregnant as they saw a tiny heart beat of approx 2mm i understand that they count it from the first day of your last period which is what they have done to me but if i was further gone would they not be able to tell me this as i keep getting told that 6 wks is too early to see a heart beat so as i would be really 5 weeks pregnant (thats when i had sex after my period) then surely it would be far too soon to see a heart beat. please help i'm really confused.

[bryanarae]

my first u/s was at 8w4d and there was a baby in there. very small obviously. we saw the heartbeat and lil tiny legs and arms and what would be the head as more development happens. and all of this was an abdominal u/s. so it all depends on when you ovulated and such. don't know if this helps at all, but thats what was visible for me at 8w4d. i believe my u/s pictures from that one are on my profile.

[kjbutcher]

I saw a heartbeat with my first son at 6w 6d and this one at 6w 2d.  They are VERY  accurate.  With my first I could not remember when my lmp was so they dated it at 6w 6d giving me a due date of 9/2.  Exactly two weeks later they said I was 8w 4d and gave me a due date of 8/31.  My son delivered on 8/31 full term.  They were right on the money!!  This time I did know my lmp which gave me a due date of 10/31.  My first scan at 6w 2d gave me a due date of 10/29, second one week later gave me a due date of 11/2 and the third one week after that gave me a due date of 10/31.  They are very veryaccurate.  Also the baby changes so quickly in the first few weeks of pregnancy that they can almost look at it and see what week you are in.  At first, under 6 weeks very small with no hb or just a sac or sac with fetal pole, at 6 weeks a blob with a hb, 7 weeks more of a gummy bear, 8 weeks a bigger gummy bear becoming more clear, 8-9 weeks a very clear shrimp shape, 10-11 weeks looks like a real baby.  So generally they can see by size within 3 days either way, but the look of the baby will tell a lot also.  So you will not be more than one week off generally.  If you have more questions, I am sure you ob will be glad to goover it with you so you understand.

[Vic85]

They can see a heartbeat at 6 weeks. I went for a scan on monday and i was 6 weeks 3 days and could see the heartbeat perfectly. I believe that is the case with most pregnancies. And I know for sure that my dates are right, congrats-sounds like you have a healthy baby in there

[amy0013]

Ultrasounds are very accurate to determine a due date because women ovulate so different in their cycles (think about it...a woman can ovulate anywhere from cycle day 8-20 so sometimes just going by the last period isn't very accurate!)  And like the other ladies said...just b/c you know when you had sex doesn't mean that is when you conceived.  Sperm can live for a while!

The ultrasound measures the size of the baby and takes the average of the measurements to determine how far along you are.  I saw the heartbeat on a transvaginal ultrasound at 5w6d.

Good luck!

[smjmekg]

Just because you had sex five weeks ago doesn't mean that you conceived that day. Sperm can live inside you for I believe 72 hours, correct me ladies if I am wrong, and there is a site online that shows statistics of when women have conceived. 221 women were in the test and 6% got pregnant having sex three or more days before they ovulated, the other 94% got pregnant having sex within two or three days of ovulation. So the day you have sex isn't necessarily the day you got pregnant. Also it can be 6-12 days (off another site) before your fertilized egg implants, and you won't show up positive on a pregnancy test until after the egg is implanted. The scan shows the size of the baby, and that's where they get the gestational age from. Hope this helped, and congrats on your baby!

[PJ466]

I'm just as confused, as far as I know they see a heart beat at about 8wks. When I went for my first scan I was 11wks and 5days( according to my calculations) but then the scan said 11wks and 1day and apparently they determined that according to the size of the baby. My due date was first 14Nov and now its 22 Nov and many women have told me that their due dates have changed quite a number of times. This can be really confusing.